Ice Ledger!

GnuCash is personal and small-business financial-accounting software, freely licensed under the GNU GPL and available for GNU/Linux, BSD, Solaris, Mac OS X and Microsoft Windows.

Tryton is a three-tiers high-level general purpose application platform under the license GPL-3 written in Python and using PostgreSQL as database engine.

The suite of applications Stoq is an innovative set of business management applications available as free and open source software.

ZipBooks allows contractors and small businesses to send quotes and invoices to potential customers or paying clients. Create a project with ZipBooks and track the time, products, and expenses of your work. Once you are ready to send an invoice to a client, ZipBooks automatically detects unbilled activity and allows you to include any or all of the billing details. You can customize the rate of each of your team members, whether to include an attached PDF, and even add your own logo to invoices. Because we make money if you use our credit card payment partners, ZipBooks is 100% free, forever. We will never spam you, show you ads, sell your information, or watermark your invoices. »

FrontAccounting is a simple, but powerful, system for the entire ERP chain and covers:

The most popular version of Americas #1 small business financial software helps make your business more profitable.

webERP is a complete web based accounting/ERP system that requires only a web-browser and pdf reader to use. It has a wide range of features suitable for many businesses particularly distributed businesses in wholesale and distribution. It is developed as an open-source application and is available as a free download to use. The feature set is continually expanding as new businesses and developers adopt it.There are on average 5,000 downloads per month.

Gnuaccounting is a Free Java cross-platform accounting and bookkeeping application.

Invoicing software & easy accounting. Create your first invoice in less than a minute. Take charge of your own accounting and get an overview of your business finances. Designed for small businesses and freelancers.

Sage 50 Accounting, previously Peachtree or Simply Accounting for Canada, delivers the efficiency your business requires whether you're after rapid expansion, steady growth, or maintaining stability. This comprehensive solution lets you easily manage customer contacts and sales, customize inventory and vendor management, automate purchasing and shipping, track jobs and projects, and more!